In water, these molecules spontaneously align â with their heads facing outward and their tails lining up in the bilayer's interior. Thus, the hydrophilic heads of the glycerophospholipids in a cell's plasma membrane face both the water-based cytoplasm and the exterior of the cell.
An MRI (magnetic resonance imaging) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the body. It does not use radiation (x-rays). Single MRI images are called slices. The images can be stored on a computer or printed on film.
MRI is the most frequently used imaging test of the brain and spinal cord. A special type of MRI is the functional MRI of the brain (fMRI). It measures the metabolic changes that occur within the brain. It may be used to examine the brain's anatomy and determine which parts of the brain are handling critical functions.